Not Applicable
Not Applicable
1. Field of the Invention
This invention relates to disk drive suspensions, and more particularly to achieving lower vertical stiffness values in a suspension while retaining in large part the torsion properties normally thought to be compromised by decreasing suspension stiffness. In a further aspect, the invention provides for the retention of intended gram load values of the suspension despite backbending of the suspension that may occur during head stack assembly, combing or other mechanical operations that cause the suspension to be bent, even briefly, along its longitudinal axis. In general, these results are realized by removing selected metal layer material from the suspension in the spring portion and in the distal portion as well. Sway resonant frequency is also improved with the invention.
2. Description of the Related Art
Each suspension application has a vertical stiffness requirement. Selection of suspension spring portion length, thickness width, within the overall size limitations imposed by the application determines the vertical stiffness, with increased width associated with increased stiffness. In general, vertical stiffness is desirably minimized. Torsional frequency response of a suspension, a function of torsion stiffness, herein generally called simply torsion, is desirably maximized and this can be done by increasing the width of the spring portion, within limits imposed by the application and the need to keep stiffness low. There is thus a trade-off between stiffness and torsion that is generally resolved by using a wide spring portion and having a hole in the center thereof to reduce the volume of metal and keep width or lateral extent up.
There is a continuing need to lower stiffness and yet maintain adequate torsion values. Ideally, the unit loss of torsion should be minimized for units of decrease in vertical stiffness. The invention has as an object the provision of a suspension design that eliminates or greatly reduces the amount of lost torsion for each increment in stiffness reduction. It is a further object to provide reduced vertical stiffness in a suspension and little or no loss in torsion. A further object is to provide a suspension in which the change in intended gram load is minimized through the utilization of the same suspension structure that provides the better ratio of torsion loss/stiffness decrease. It is a specific object to provide a suspension in which there is an aperturing locally in the spring portion carrying on to the base and/or distal portion of the suspension that enables a decrease in suspension stiffness at little or no loss in torsion. The discontinuity further acts to allow the plastic film part of the suspension laminate to avoid stretching with the metal layer part of the laminate during backbending of the suspension by passing through the discontinuity instead of bending arcuately with the metal layer. The problem of the stretched plastic film changing the suspension intended gram load is thus avoided.
These and other objects of the invention to become apparent hereinafter are realized in low stiffness, high torsion disk drive suspension having an intended gram load and comprising a laminate of a metal layer and a subassembly comprising a plastic film layer and a plurality of conductors, the support comprising a base portion, a spring portion defined by the laminate, and a distal portion, the spring portion and either or both of the base portion and the distal portion being locally discontinuous to permit the subassembly to pass through the plane of the spring portion upon bending of the spring portion, whereby stretching of the plastic film and resultant change in intended gram load is limited.
In a further embodiment, the invention provides a suspension comprising a laminate having a proximate part and a distal part, the laminate comprising a metal layer and a subassembly comprising a plastic film layer and a plurality of conductors, and a support for said laminate, the laminate comprising a base portion, a first spring portion and a distal portion; the laminate metal layer defining a second spring portion and being locally discontinuous to permit the subassembly to pass through the plane of the second spring portion upon bending of the laminate, whereby stretching of the plastic film and resultant change in intended gram load is limited.
In a further embodiment, the invention provides a low stiffness, high torsion disk drive suspension having an intended gram load and comprising a laminate of a metal layer and a subassembly comprising a plastic film layer and a plurality of conductors, the laminate metal layer comprising a base portion, a spring portion traversed by an extent of said subassembly, and a distal portion, the metal layer being locally discontinuous opposite the subassembly extent to permit the subassembly extent to pass through the plane of the spring portion upon bending of the spring portion away from said subassembly extent, whereby stretching of the plastic film and resultant change in intended gram load are reduced from that occurring when the subassembly is bent with the spring portion and its film layer stretched.
In these embodiments, typically, the metal layer comprises stainless steel, the plastic film comprises a polyimide film, the stiffener comprises a stainless steel member of greater stiffness than the laminate metal layer, the stiffener supporting the distal portion, and typically attached to and generally congruent with the opposing part of the laminate distal portion, the discontinuity is a first discontinuity and has a longitudinal extent substantially equal to the length of the spring portion and has a lateral extent equal to about 35% to about 70% of the width or lateral extent of the spring portion, the laminate distal portion can have a second discontinuity contiguous with the first discontinuity and have a lateral extent equal to about 35% to about 70% of the width or lateral extent of the spring portion, the laminate has a base portion, the base portion defining a third discontinuity contiguous with the first discontinuity and having a lateral extent equal to about 35% to about 70% of the width of the spring portion.
In further embodiments, typically, the metal layer defines a base portion, the noted discontinuity is a first discontinuity, the laminate metal layer defining one or both of a second and third discontinuity in the laminate distal portion and the laminate base portion respectively, the discontinuities each being contiguous with the first discontinuity, each having a longitudinal extent substantially equal to the length of the spring portion, and each having a lateral extent equal to about 35% to about 70% of the width or lateral extent of the spring portion, each of the discontinuities is centered on the metal layer longitudinal axis, the subassembly being centered on the metal layer longitudinal axis and having less lateral extent than the discontinuities.
In a still further embodiment, the invention provides a low stiffness, high torsion disk drive suspension having an intended gram load and comprising a laminate having a proximate part and a distal part, the laminate comprising a metal layer and a subassembly comprising a plastic film layer and a plurality of conductors, and a laminate support, the support comprising a base portion, a spring portion, and a distal portion comprising a stiffener, the metal layer being locally discontinuous to permit the subassembly to pass through the plane of the spring portion upon bending of the laminate away from said subassembly, whereby stretching of the plastic film and resultant change in intended gram load is limited.
In this and like embodiments, the metal layer comprises stainless steel, the spring portion comprises stainless steel, the plastic film comprises a polyimide film, there can further be present a stiffener that is a stainless steel member of greater stiffness than the metal layer distal portion, the stiffener being attached to and generally congruent with the part of the metal layer distal portion it opposes, the discontinuity is a first discontinuity and has a longitudinal extent substantially equal to the longitudinal extent of the spring portion, and a lateral extent equal to about 35% to about 70% of the width of the spring portion that can be uniform or variable, e.g. the discontinuity is a first discontinuity and has a uniform lateral extent equal to about 35% to about 70% of the width of the spring portion, or the discontinuity is a first discontinuity and has a varying lateral extent over its longitudinal extent between about 35% and about 70% of the width of the spring portion, to be in this embodiment, or other embodiments herein, a closed figure of e.g. polygonal, rectangular, circular, cruciform, oval, circular, or other closed figure shape, or such shapes that open forwardly or rearwardly to the laminate proximate part or distal part.
As in previous embodiments, the laminate distal part can define a second discontinuity contiguous with the first discontinuity, the second discontinuity having a lateral extent from about 35% to about 70% of the width of the spring portion, the laminate proximate part a third discontinuity contiguous with the first discontinuity, the third discontinuity having a lateral extent from about 35% to about 70% of the width of the spring portion, or where the discontinuity is a first discontinuity, and the laminate defines one or both of a second and third discontinuity in the laminate distal part and the laminate proximate part respectively, the discontinuities each being contiguous with the first discontinuity, each having a longitudinal extent less than the longitudinal length of the spring portion, and each having a lateral extent from about 35% to about 70% of the lateral extent of the spring portion.
Typically, each of the discontinuities is centered on the metal layer longitudinal axis, the subassembly being centered on the metal layer longitudinal axis and having less lateral extent than the discontinuities, and the stiffener opposes the second discontinuity.
In a further embodiment, the invention provides a disk drive suspension for mounting by a mounting plate having a distal edge, and comprising a laminate of a metal layer and a subassembly of a plastic film layer and a plurality of conductors separated from the metal layer by the plastic film layer, the laminate having a proximate base portion substantially free of the conductors and adapted to be mounted to an actuator with the mounting plate, a distal portion adapted to mount a slider electrically connected to the conductors, and a spring portion extending in a plane between the proximate and distal portions; and a stiffener fixed to the distal portion forward of the spring portion in opposing relation, the stiffener having a proximate edge opposite the mount plate distal edge, the metal layer defining between the proximate and distal edges a first region that extends in a plane generally parallel with the spring portion plane and having substantially the length and width of the spring portion, the first region defining a first discontinuity whereby the subassembly is substantially free of the metal layer within the first region; the metal layer defining a second region contiguous and substantially coplanar with and distal to the first region and oppositely adjacent and generally parallel with the stiffener, the second region defining a second discontinuity that is a continuation of the first region discontinuity whereby the subassembly is substantially free of the metal layer within the second region, the subassembly moving independently of the metal layer at first and second discontinuities, said subassembly moving in response to backbending of the metal layer in an arc through the metal layer at the discontinuities therein rather than stretching fully over the arc of the bent metal layer as a function of the presence of the first and second discontinuities in the metal layer opposite the subassembly to lessen any change in the intended gram load resultant from stretching of the plastic film layer in the subassembly.
In its method aspects the invention provides the method of limiting gram load changes in a disk drive suspension comprising a suspension laminate of a metal layer and a subassembly of a plastic film and a plurality of conductors that has a base portion, a spring portion and a distal portion, including defining a discontinuity in the metal layer of the spring portion sized to pass the subassembly in the bent condition of the metal layer away from said subassembly through the plane of the spring portion, and passing the subassembly through the discontinuity chordally to the arc of the bent spring portion against stretching of the plastic film along the arc and thereby changing the gram load of the suspension.
Typically, the method also includes defining one or both of a second and third discontinuity in the metal layer distal portion and base portion respectively that is contiguous with the spring portion discontinuity, and passing the subassembly through the spring portion and the distal portion discontinuities chordally to the arc of the spring portion against stretching of the plastic film along the arc and thereby changing the gram load of the suspension, and further stiffening the distal portion with the stiffener.